An image processing method has been proposed in which the respective positions of both eyes are detected in a photographic image of a face, and a chin area including the location of the chin and a region in the vicinity of the chin is estimated based on the respective positions of the two eyes. The position of the chin is then detected within the chin area, from which non-skin colored pixels have been removed. In this image processing method, pixel values of each pixel in the estimated chin area are projected onto an axis in the vertical direction of the face, and projection data is obtained at each height in the axial direction. Edge strength is then derived for each height based on the projection data, and the positions of the pixels corresponding to the height with the greatest edge strength is determined to be the position of the chin.
A chin position computation device that computes the position of the chin from a received color image has also been proposed. In this device, a skin-colored face is detected in the color image, and, based on the detected face, a reference line is computed from a central position between the two eyes and a central position of the mouth of the face. Data expressing a statistical positional relationship between the central position between the two eyes, the central position of the mouth, and the position of the chin is acquired, and a probability for the position of the chin of the face is computed from the data expressing positional relationships and from the computed reference line. A probability for the presence of skin-colored pixels on the reference line is also computed, and a rate of change in luminosity on the reference line is also computed. The position of the chin is computed from a result of combining the respective computed probability and rate.
An image processing device has been proposed in which a luminosity difference from peripheral pixels is derived for each pixel in original image data, and an outline level that determines the luminosity of these pixels in outline image data is evaluated based on a luminosity gradient. In this image processing device, the outline levels of pixels with a luminosity gradient absolute value that is greater than a threshold value are moved in a specific direction according to the slope direction of the luminosity gradient.